Camshaft-adjusting devices, particularly those that work hydraulically, are mainly used in internal combustion engines. Insofar as the camshaft adjuster works hydraulically, as is typical, it exhibits an impeller, in which blades are incorporated or arranged. The blades are located in hydraulic chambers, which are incorporated in a drive element (also referred to as an external rotor or stator). Through the corresponding application of hydraulic fluid to the respective side of the hydraulic chambers, the internal rotor (connected to the camshaft) may be adjusted relative to the external rotor between an “early limit stop” and a “late limit stop”. The flow of hydraulic oil in this case is controlled by an electrically actuated directional valve. The transmission of the rotational movement of the crankshaft to the external rotor mainly takes place via a gear-wheel, to which the external rotor is connected in a non-rotatable manner. A camshaft adjuster and also a control valve of the aforementioned kind is disclosed in DE 102 11 468 A1, for example. In this solution, the device has a vane-type design. Other variants are also known, however, such as axial piston adjusters from DE 42 18 082 A1, for example.
The camshaft is mounted in a cylinder head of the internal combustion engine by means of a plurality of camshaft bearings. Hydraulic fluid is supplied to a hydraulic fluid channel formed in the camshaft via one of the camshaft bearings, which hydraulic fluid can be conducted into the pressure chambers via the control valve, which is arranged in a receiving part of the camshaft.
The control valve comprises a valve housing and a control piston contained in the valve housing in an axially displaceable manner. The control piston may be positioned by means of an electromagnetic actuator against the force of a spring element in an axial direction relative to the valve housing and thereby control the hydraulic fluid flows.
A circlip may be used to fix the valve housing. In this case, a form-fit fixing of the valve housing in the camshaft or in the rotor is achieved by means of the circlip. A solution of this kind is disclosed in DE 10 2009 039 085 A1 and DE 10 2009 039 384 A1.